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Age and origin of a Palaeozoic nepheline syenite from northern Shanxi Province, China: U–Pb zircon age and whole-rock geochemical and Sr–Nd isotopic constraints.
- Source :
-
International Geology Review . Aug2012, Vol. 54 Issue 11, p1296-1308. 13p. - Publication Year :
- 2012
-
Abstract
- Geochronological, geochemical, and whole-rock Sr–Nd isotopic analyses were performed on a suite of Palaeozoic nepheline syenites from Zijinshan to characterize their ages and petrogenesis. Laser ablation inductively coupled plasma-mass spectrometry U–Pb zircon analyses yield consistent ages of 525.7 ± 2.8 million years for a sample (HYK01). These intrusive rocks belong to the foid syenite magma series in terms of K2O + Na2O contents (14.3–15.2 wt.%) and to the shoshonitic series based on their high K2O contents (5.42–5.61 wt.%). The nepheline syenites are further characterized by high light rare earth element contents [(La/Yb) N = 29.1–36.1]; show modest negative Eu anomalies (δEu = 0.5–0.6) and positive anomalies in Rb, Th, U, Pb, Zr, and Hf; are depleted in Ba and high field strength elements (P and Ti). In addition, all the nepheline syenites in this study display relatively low radiogenic Sr (87Sr/86Sr) i (0.7042–0.7043) and positive ϵNd (t) (0.7–0.8). These results suggest that the nepheline syenites were derived from depleted continental crust. The parent magmas likely experienced fractional crystallization of plagioclase, Ti-bearing oxides (e.g. rutile, ilmenite, and titanite), apatite, and zircon during ascent, with negligible crustal contamination before final emplacement at a high crustal level. [ABSTRACT FROM PUBLISHER]
Details
- Language :
- English
- ISSN :
- 00206814
- Volume :
- 54
- Issue :
- 11
- Database :
- Academic Search Index
- Journal :
- International Geology Review
- Publication Type :
- Academic Journal
- Accession number :
- 77491991
- Full Text :
- https://doi.org/10.1080/00206814.2011.638436